Lasing at 150 μm wavelength and measurement of the characteristics of the free-electron laser at ISIR, Osaka University

We are conducting FEL experiments using the infrared FEL system based on the L-band electron linac at ISIR, Osaka University, to extend the wavelength region toward the longer-wavelength side and to study FEL dynamics in the long wavelength region. The FEL wavelength was extended to 150 μm, which is the longest wavelength so far obtained with FELs based on RF linacs. We observed a phenomenon that FEL oscillation was obtained at two different optical cavity lengths but not in between them.